Gliederung

Treatment of low grade glioma of the optic pathway is a challenging issue for the radiooncologist owing to their low incidence and controversies about "optimal" treatment approach. Despite uncertainties concerning indications, age at treatment, dose-response, timing and use of "optimal" treatment fields, radiation therapy continues to play an important role in the management of these tumours achieving long term survival rates up to 80% or more. In gliomas of the visual pathway, high local tumour control and improved or stable visual function is achieved in approximately 90 % of cases. Data on dose response relationships recommend dose prescriptions between 45 Gy and 54 Gy with standard fractionation. There is consensus now to employ radiation therapy in older children in case of progressive disease only, regardless of tumour location and histological subtype. In younger children the role of radiotherapy is unclear. Recent advances in treatment techniques, such as 3D treatment planning and various "high-precision" treatments achieved promising initial outcome, however with limited patient numbers and short follow-ups. According to an interim analysis of the prospective HIT SIOP LGG 1996 study 42 children out of 198 (21,2%) of the german cohort of patients with gliomas of the optic pathway were irradiated, 27 as first non-surgical therapy and 15 with progress after initial chemotherapy. 17 patients received conventional fractionated external radiotherapy, 7 stereotactical fractionated irradiation and 7 brachytherapy (information regarding 1 case is missing). After a median observation time of 50.1 months, 22 tumours (77,8%) in the group of the children with radiotherapy as first treatment are stabilised and 3 (11,1%) showed partial response. 1 child has deceased, one was not evaluable.

Conclusion

More prospective studies are needed to address the impact of modern radiation therapy technologies (including intensity modulated radiotherapy) in the management of gliomas of the optic pathway on outcome especially in the very young and to define the role of radiation therapy as a part of a comprehensive treatment approach. The forthcoming prospective trial SIOP/GPOH - LGG RT 2004 is addressing this issue.